Question

我有一个分组的ListView。添加新项目时，ListView的内容不会更新。我该如何解决？这是我的代码：

练习课：

let localizedJSONObject = try LocalizedJSONObject(json)

用于分组项目的类：

    public class Exercise : INotifyPropertyChanged
{
    public enum muscleGroups
    {
        None,
        Back,
        Chest
    }

    public Exercise() { }

    private string title { get; set; }
    private muscleGroups muscleGroup { get; set; }

    public string Title
    {
        get { return title; }
        set
        {
            if (title != value)
            {
                title = value;
                OnPropertyChanged("Title");
            }
        }
    }

    public muscleGroups MuscleGroup
    {
        get { return muscleGroup; }
        set
        {
            if (muscleGroup != value)
            {
                muscleGroup = value;
                OnPropertyChanged("MuscleGroup");
            }
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    public void OnPropertyChanged(string prop = "")
    {
        if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(prop));
    }

}

将分组项添加到ListView（名称exerciseList）中，按MuscleGroup属性的值进行分组：

    public class ExerciseGrouping<K, T> : ObservableCollection<T>
{
    public K Name { get; private set; }

    public ExerciseGrouping(K name, IEnumerable<T> items)
    {
        Name = name;
        foreach (T item in items)
            Items.Add(item);
    }
}

添加新项目时，如何更新ListView的内容？提前谢谢。

添加新项目的代码（我有另一页练习页面来编辑或添加新项目）：

            Exercises = new ObservableCollection<Exercise>
        {
            new Exercise {Title="Exercise 1", MuscleGroup = Exercise.muscleGroups.Chest},
            new Exercise {Title="Exercise 2", MuscleGroup = Exercise.muscleGroups.Chest},
            new Exercise {Title="Exercise 3", MuscleGroup = Exercise.muscleGroups.Back},
            new Exercise {Title="Exercise 4", MuscleGroup = Exercise.muscleGroups.Back}
        };

        var groups = Exercises.GroupBy(p => p.MuscleGroup).Select(g => new ExerciseGrouping<Exercise.muscleGroups, Exercise>(g.Key, g));
        ExerciseGroups = new ObservableCollection<ExerciseGrouping<Exercise.muscleGroups, Exercise>>(groups);

        //exercisesList.BindingContext = Exercises;
        exercisesList.BindingContext = ExerciseGroups;

ListView内容更新（Xamarin.Forms）

0 个答案: